Dobby could be a great butler. He was always eager to serve Harry and was very loyal. His knowledge of the Malfoy manor and other wizarding households could be useful. And his unique brand of magic, like his ability to apparate in and out of places where other wizards couldn't, would add an interesting dynamic to the story.
One possible plot could be that the butler is actually a wizard in disguise who has been sent to protect Harry. He could use his knowledge of the wizarding and Muggle worlds to keep Harry safe from both magical threats like Death Eaters and Muggle dangers. For example, he could use his connections in the Muggle world to find safe houses for Harry when he needs to hide from Voldemort.
Yes, there might be some fanfiction that has such an interesting and rather unique concept. Some fanfic writers like to create crossovers and put unexpected twists in them. They might imagine Harry Potter as a cat within the world of Black Butler for various reasons, like exploring different character dynamics or just for the fun of it.
In Harry Potter fanfiction, a cat could be a magical familiar. For example, it might be a cat that can transform into a wizard's assistant when needed. In Black Butler fanfiction, a cat could be part of the Victorian - era setting, perhaps a stray that Ciel and Sebastian encounter on the streets of London.
I think Sir Ian McKellen would be a great choice. He has that air of elegance and mystery about him. His acting skills are top - notch and he could bring a lot of depth to the role of the butler.
One idea could be a crossover where the characters from Harry Potter end up in the world of Black Butler. For example, Harry, Hermione and Ron could be mistaken for some kind of strange magical beings in the Victorian era of Black Butler. They might be brought to the Phantomhive manor and Sebastian has to figure out what to do with them. Maybe they are there to solve a mystery that involves both the magic of the Harry Potter world and the dark secrets in the Black Butler universe.
Dobby could be a great character as a butler in fanfiction. He already has a strong loyalty to Harry and his self - sacrificing nature would make him an excellent butler. He could use his house - elf magic to keep Harry's living quarters clean and protected.
Another theme is the moral grayness. Both universes have characters that exist in that morally ambiguous area. Fanfictions tend to play with this, like when characters from Harry Potter are faced with the more cut - throat and often morally complex situations in the Black Butler world. For example, how would Harry react to some of the deals and sacrifices that are common in the Black Butler world? It makes for some really thought - provoking reading.
One great Black Butler and Harry Potter crossover fanfiction is 'A Butler in Hogwarts'. It has an interesting plot where Sebastian, from Black Butler, somehow ends up in the wizarding world of Harry Potter. He uses his skills to navigate the strange new place while also causing some chaos. Another good one could be 'The Dark Arts of a Demon Butler'. It combines the dark elements of both universes really well.
Another good one is 'The Potter - Phantomhive Connection'. This fanfiction delves deep into the relationship between a fem Harry Potter and the Phantomhive household. It shows how her presence disrupts and also enriches the existing dynamics. The writing is quite engaging, with detailed descriptions of the settings and the characters' emotions.